Preheat oven to 350 degrees F (175 degrees C). Grease and flour two 9x5 inch loaf pans.

In a large bowl, cream together the softened butter, softened cream cheese, and sugar until light and fluffy.

Beat in the vanilla extract and eggs, one at a time, until well combined.

In a separate bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.

Gently fold in the flour-coated blueberries.

Divide the batter evenly between the prepared loaf pans. The batter will be thick.

Bake for 50-60 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the loaves cool in the pans for 10-15 minutes before transferring them to a wire rack to cool completely.